So i have had my MBP for over a year now and i was thinking of upgrading the RAM. so i went into my town and bought second hand:- 2 x 2GB DDR2 - PC2-6400s Nanya RAM. ( a make i have never heard of, but upon looking i have found they arent a small company) so i have placed them in my MBP properly to find out it doesnt turn on, the LED on the front turns on and the CD drive starts up but then nothingness!. Can someone help me as to why it wont, and also if this RAM is compatible on my MBP as there arent any lists stating compatible RAM modules. Any help would be great! Alex Ps. Both RAM modules work perfectly in my Fiancée's Windows laptop. so i know they are in good shape.